I get blocks sometimes and those worde too but I can always get past them. Try saying the first syllable as you exhale from your mouth. Almost simultaneously. There is one word I have never been able to say. The word “did”. I can’t start a sentence with it. There were times when I could but that happened without me thinking about the word. Ive never been able to intentionally lead a question by asking someone “did you do this/ did you have a chance to / etc.